STMicroelectronics T835T-8FP

Overview

T835T-8FP from STMicroelectronics is a snubberless, 3-quadrant, 8 A rms medium-current triac in TO-220FPAB package, rated for 800 V repetitive off-state voltage (VDRM/VRRM), 900 V non-repetitive surge (VDSM/VRSM), and 100 A/µs critical dI/dt. It delivers high static/dynamic commutation capability and operates without external snubber circuits when used within datasheet-defined limits, supporting AC line switching in motor control and lighting.

For engineers reviewing the T835T-8FP datasheet, T835T-8FP pinout, T835T-8FP application, or T835T-8FP equivalent, key selection criteria include its 3.8 °C/W junction-to-case thermal resistance, 2 kV UL-certified insulation, 35 mA gate trigger current, and validated 125 °C/150 °C operation at 800 V/600 V blocking levels - all critical for reliable AC power control in thermally constrained environments.

Technical Context

The T835T-8FP is a three-quadrant triac optimized for high commutation robustness: it supports triggering in Quadrants I, II, and III but excludes QIV, reducing false turn-on risk under noisy AC conditions. Its Snubberless™ architecture eliminates need for RC snubbers when dV/dt remains ≤2000 V/µs (Tj = 125 °C) and (dI/dt)c ≥8 A/ms (Tj = 125 °C).

It features a low on-state voltage of 1.55 V (max, Tj = 25 °C) and dynamic resistance of 57 mΩ (max, Tj = 150 °C), enabling efficient conduction at 8 A rms with minimal self-heating. The device's 2 kV rms insulation rating and UL E81734 certification support reinforced isolation in mains-connected equipment.

Key Specifications

Pinout & Package

Package: TO-220FPAB - insulated through-hole package with integral heatsink tab, lead-free, UL94 V0 epoxy, and 0.4–0.6 N·m mounting torque specification.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triac-based AC switching applications.

Compared with BT139-800E and T835-800B, the T835T-8FP uniquely combines snubberless operation, UL-certified 2 kV insulation, and 8 A/800 V rating in one TO-220FPAB package - delivering system-level simplification, safety compliance, and thermal headroom not available in either alternative.

Availability

T835T-8FP is available at Aetrix Electronics and suitable for motor control, lighting dimming, and inrush limiting applications requiring stable component supply, long-lifecycle assurance, and certified safety compliance.

Supply support for T835T-8FP includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The T835T-8FP belongs to ST's Snubberless™ Triac product line, engineered specifically for robust, snubber-free AC power control in cost-sensitive, space-constrained, and safety-critical applications such as home appliances and industrial controls.

FAQ

Can the T835T-8FP operate without a snubber circuit?

Yes - the T835T-8FP is explicitly designed as a Snubberless™ triac and can operate without an external RC snubber when operating conditions respect datasheet limits: dV/dt ≤2000 V/µs (Tj = 125 °C), (dI/dt)c ≥8 A/ms, and blocking voltage ≤800 V at Tj ≤125 °C. These constraints are verified per IEC 61000-4-4 and UL 60730 test protocols.

What is the maximum junction temperature and how does it affect blocking voltage?

The T835T-8FP has a maximum junction temperature of +150 °C. At this temperature, its rated repetitive blocking voltage drops to 600 V (VDRM/VRRM), whereas it maintains 800 V at Tj ≤125 °C. This derating is defined in Table 2 and must be accounted for in thermal design to avoid premature breakdown under high ambient or high-power conditions.

Is the T835T-8FP compatible with standard TO-220 heatsinks?

Yes - the TO-220FPAB package uses the same footprint and mounting hole pattern as standard TO-220AB, but with an insulated tab. It accepts industry-standard TO-220 clip-on or bolt-down heatsinks; however, thermal interface material must be applied between the insulated tab and heatsink surface to maintain electrical isolation while enabling effective heat transfer.

Does the T835T-8FP support four-quadrant triggering?

No - the T835T-8FP is a three-quadrant triac, supporting gate triggering only in Quadrants I, II, and III. Quadrant IV triggering is intentionally disabled to prevent false turn-on caused by negative gate noise during high dv/dt transients, enhancing reliability in electrically noisy AC environments such as motor drives and dimmers.